Dalmatian jasper meaning3/16/2023 ![]() ![]() ![]() If you are struggling with the identity of this material, here is what we encourage you to do. They don't like giving up the word "jasper" for this material, or they insist that the black material is schorl tourmaline. So, instead of being a jasper, Dalmatian Stone is an igneous rock.Ī few people have contacted us about what we have written above. The types of minerals in the rock are those that crystallize from a melt. It is a mixture of minerals and therefore it is a rock. Jasper is a microcrystalline variety of quartz, but the composition of our Dalmatian Stone is much more interesting. The white material is a mixture of the mineral albite, a plagioclase feldspar with a composition of Na(AlSi 3O 8), and lesser amounts of quartz (SiO 2). John's analysis determined that the black material is the mineral arfvedsonite, an amphibole similar to hornblende, with a composition of Na 3(Fe,Mg) 4FeSi 8O 22(F,OH) 2. He used that to isolate some of the black material from the light matrix. He crushed the specimens and determined that the black material was very slightly magnetic. We decided to send a few pieces to John Attard for x-ray diffraction, a laboratory analysis that identifies minerals and other materials with a crystalline structure. Coarsely crystalline Dalmatian Stone might look something like this. ![]() A mineral specimen from Malawi that presents arfvedsonite on a base of feldspar. ![]()
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